INFO VISUALIZATION: Here's a great way to visualize music. "The Shape of Song" takes a midi file and connects similar note structures with each other using an arch. In their words:

The diagrams in The Shape of Song display musical form as a sequence of translucent arches. Each arch connects two repeated, identical passages of a composition. By using repeated passages as signposts, the diagram illustrates the deep structure of the composition.

It works very well and can actually inform you a bit about the song's underlying structure. Highly repetetive pieces will have a large amount of uniformly connected arches; simple songs will have very thick and wide arches; complex and erratic songs will have more chaotic patterns. Pictured above? "Women" by Def Leppard.